Valve arrangement for fluid pressure motor or pump

ABSTRACT

The invention relates to a gerotor type motor or pump in which the valving is between the gerotor star member and the adjacent casing wall. A separate valve member, as such, is not provided. The valving includes recesses formed in the star, each of which sequentially moves into fluid communication with inlet and outlet recesses formed in the casing wall. The star member has the usual combined rotary and orbital movements and the valve recesses are accordingly formed or shaped to accommodate this compound movement.

United States Patent 1 Petersen et al.

[ VALVE ARRANGEMENT FOR FLUID PRESSURE MOTOR oR PUMP [75] Inventors: Carsten Georg Otto Petersen, Hohe Buch; Svend Giversen, Ulkebol, both of Denmark [73] Assignee: Danfoss A/S, Nordberg, Denmark [22] Filed: Nov. 10, 1972 [21] Appl. No.: 305,599

[30] Foreign Application Priority Data Nov. 10, 1971 Germany 2155818 [52] US. Cl 418/61 B [51] Int. Cl. F04c 1/06 [58] Field of Search 418/61, 186

[56] References Cited UNITED STATES PATENTS 2,989,951 6/1961 Charlson. 418/61 X 3,567,349 3/1971 Meulendyk 418/61 [451 July 23, 1974 r 3,680,987 8/1972 Ohrberg 418/61 3,736,078 5/1973 Read 418/61 X FOREIGN PATENTS OR APPLICATIONS 385,797 l/1933 Great Britain 418/61 396,857 8/1933 Great Britain 418/61 Primary ExaminerC. J. Husar Assistant ExaminerLeonard Smith [5 7 ABSTRACT The invention relates to a gerotor type motor or pump in which the valving is between-the gerotor star member and the adjacent casing wall. A separate valve member, as such, is not provided. The valving includes recesses formed in the star, each of which sequentially moves into fluid communication with inlet and outlet recesses formed in the casing wall. The star member has the usual combined rotary and orbital movements and the valve recesses are accordingly formed or shaped to accommodate this compound movement.

- 5 Claims, 4 Drawing Figures PATENTimmza 1924. 3,8253? 6 SHEET 1 or 3 a 1 VALVE ARRANGEMENT FOR FLUID PRESSURE MOTOR OR PUMP The invention relates to an internal shaft meshing rotary piston machine in which two toothed elements, i.e., an externally toothed wheel and an internally toothed ring execute a circular movement and a rotary movement relatively to each other, and the displacement chambers formed between the teeth are connected to the delivery and discharge sides through a distributor valve which is formed in at least one plane extending at right angles to the axes of the toothed elements and which comprises a first set of valve openings, which are associated with the toothed wheel and are preferably formed therein and are disposed substantially along an are about the center point of the toothed wheel, and a second set of valve openings which areassociated with the toothed ring and are disposed substantially along an arc about the center point of the toothed ring.

Internal shaft rotary piston machines of this kind usually comprise a toothed wheel which has one tooth less than the toothed ring. The speed of revolution at which the displacement chambers in a pump are alternately connected to the compression side and the intake side, and in a motor, to the high pressure side and the low pressure side is a multiple of the rotary speed of the main shaft of the machine. The distributor valve ensures that the displacement chambers are connected to the supply and discharge sides respectively in the correct order and at the correct speed of revolution.

In a known rotary piston machine of this kind (U.S. Pat. Specification No. 3,233,524), the toothed ring is secured to the casing and the toothed wheel executes the circular and rotary movement. For this purpose, it is connected to the main shaft through a universal joint shaft. To form the distributor valve, grooves are formed in the two faces of the toothed wheel, and bores in adjacent sidewalls solid with the casing. The bores in one of the sidewalls are connected to the supply side and those in the other sidewall to the discharge side. Each set of bores is disposed along an arc which is concentric with the centre-point of the toothed ring. The number of bores corresponds to the number of teeth on the ring. The grooves are disposed substantially along circumferential portions of an arc which is concentric with the centerpoint of the toothed ring and is larger than the are along which the bores are located. The number of grooves is equal to the number of teeth on the wheel. Each groove is connected by way of an extension to a flank of a tooth offset in the circumferential direction. The extensions for the supply side grooves extend in one circumferential direction and those for the discharge side grooves in the other circumferential direction. As a result of the differences in the arc diameters, the grooves move into and out of contact with the associated bores in deependence upon the circular movement.

In this construction the grooves have a circumferential length which is at least equal to the distance between adjacent bores. In conjunction with the extensions long connecting passages which therefore have a flow restricting efiect are obtained. Furthermore, the formation of these grooves involves difficulties. Use has to be made of both faces of the toothed wheel for the purpose of forming the distributor valve.

Generally, however, coaxial distributor valves are used; a construction is known, for example (U.S. Pat. Specification No. 2,989,951), in which the toothed wheel rotates and the toothed ring moves over a circular path. In this arrangement, the toothed wheel comprises valve openings on both of its faces, these openings being formed by bores, and are disposed along an arc concentric with the centerpoint of the toothed wheel and are connected to the chambers. Bores constituting valve openings are formed in two adjacent sidewalls, and the valve openings are disposed along arcs having the same diameter and centerpoint. These sidewalls are solid with the casing. Since the toothed ring executes a movement relative to the associated valve openings, slight displacements can take place during operation and these adversely affect the functioning of the valve.

Also known are rotary piston machines (U.S. Pat. Specification No. 3,087,436), in which the valve openings arenot located in planesextending at right angles to the axes of the toothed elements, but over a cylindrical surface. Here again, a fixed toothed ring cooperates with a toothed wheel which executes rotary and circular movements. Valve openings connected to the chambers extend froma bore in the casing. The number of these valve openings corresponds to the number of teeth on the ring. Valve openings alternately connected to the supply and. discharge sides are provided on the outside of a rotary slide. The number of the openings corresponds to twice that-of the teeth. on thewheel. The width of the valve openings is so selected that the distance between adjacent valve openings on the rotary slide is slightly greater than the width of the first named valve openings in the circumferential direction.

The object of the present invention is that of so improving an internal shaft rotary piston machine of the initially stated kind in which the distributor valve openings are connected to the associated toothed element that shorter flow paths and a simpler construction can be achieved.

According to the invention, and in the case where use is made of the circumferential distribution of the valve openings of both sets, which is known in the case of a coaxial distributor valveand whereby the valve openings are temporarilyin register in dependence upon the relative rotary movement, the above object is achieved by the radial component of the valve openings being so great that despite the circular movement superposed upon the rotary movement, the valve openings remain in register.

Since in this arrangement the functioning of the valve is largely dependent upon the rotary movement, no passage is required for joining the valve openings of the one set to chambers offset through approximately 90.

. Instead, use can be made of short connecting passages which offer slight resistance to flow and can be easily bored. It is even possible to arrange the entire distributor valve in a plane extending at right angles to the axes of the toothed elements. The valve openings are nevertheless positively associated with the related toothed elements so that very precise functioning of the valve results.

It is of advantage if the valve openings of at least one set have a radial component which is at least equal to the diameter of the-path of the circular movement. This requirement can, however, also be met if the valve I 3 Openings of both sets have a corresponding'radial component.

- The valve openings of both sets are in register over aparticularly large extent, and the flow resistance is therefore particularly small if the sum of those portions of the radial components of two valve openings that overshoot the radial width of register isequal to the diameterof the path of the circular movement.

For the purpose of achieving the necessary radial component, it is advisable for the main direction of the valve openings of a set, and particularly of the openings connected to the chambers, to extend in the radial di- 'cutesa circular movement, the valve openings conplacement chambers fromthe left, the location of the rection. The same purpose is served if the valve openthrough a point on the line of valve openings of the other set when the circular and rotary movements take place.

- Ina preferred arrangement, the valve openings connected tothe chambers are formed by substantially ra dial grooves extending to the outer circumference of the toothed wheel or the inner circumference of the toothed ring. This results in extremely short flow passages having a small resistance to flow. Furthermore, these grooves can-be formed very easily, e.g., by grindmg. I 1

, Also, the grooves mayterminate at the middle of the bases of the teeth. The cross-section of the groove, acting as a valve opening, can'then move close to the base of the teeth in each case.

It is also advisable for the valve openings to be of triangular form and to widen towards the circumference. The triangular form reduces the resistance toflow and enables the valve openings of the other set to be brought. closer together in places. I

Increase in the depth of the grooves towards the circumference also serves the purpose of reducing resistance to flow.

The width of each groove at the circumference of one of the toothed elements is expediently so great that when theother toothed element moves into engagement with the crest of the tooth, communication between adjacent chambers is established by way of the groove. In this way, it is possibleto inhibit sudden increases in pressure which could occur upon overtravel from one valve opening to another.

In a preferred arrangement, the valve openings connected to the supply and discharge sides have a shape in which when a chamber'having maximum volume is formed one long side runs close to that circumference of the toothed element presented to this chamber. In this way, it becomes possible to locate the valve opening as far away as possible from the centre point of the associated toothed element, so that the valve openings may have a relatively large cross section.

Thevalve'openings connected to the supply and discharge sides may also be of substantially rectangular form in which one short side when a chamber having maximum volume is formed runs close to one of the sides of the valve opening connected to this chamber, and the other short side when a relative movement equal to one-half of the pitch of the teeth has taken place runs close to the other side of thisvalve open- A particularly simple machine is obtained if the toothed ring is fixed, the toothed wheel rotates and exefixed valve openings also being shown for a position where the chambers are'at maximum volume,

FIG. 3 shows the details of FIG. 2 but with the chambers at minimum volume, and

FIG. 4 shows details of FIG. 2 for any given rotary position. i

. The rotary piston machine has a casing comprising a first cover plate 1, a bearing block 2, a first side disc 3, a toothed ring 4, a second side disc Sand a second cover-plate 6. The said parts are interconnected by means of screw-bolts 7'and 8. The teeth on the ring 4 are constituted by cylindrical rollers 9. Rollers 9 are, retained in the ring 4 by reason, of the ring having recesses as shown in which the rollers are disposed. Each of therecesse's has a concave cylindrically shaped surface which retains a cylindrically shapedroller by reason of the recess being somewhat greater than semicylindrical in shape. A'main shaft 10 is mounted in the bearing block 2. Thismain shaft is connected to and drives a toothed wheel 12 through a universal joint shaft 1 1-. The second cover-plate 6 comprises a supply port 13 and a discharge port 14. Anaxial inlet passage or bore I5and radial passages 16 lead from the supply port l3to valve inlet port openings 17. A transverse outlet passage or bore 18, an annular passage 19 and radial grooves 20 lead from the discharge port 14 to valve outlet port openings 21. Formed in the toothed wheel 12 are radial grooves 22 which constitute valve distributor port openings 23 at the face of the wheel. The stationary valve inlet and outlet openings 17 and 21 constitute a first set, and the movable valve distributor port openings 23 a second set. The functions of theports l3 and 14 can also be changed over, e.g., when the direction of rotation is reversed. Displacement chambers 24 into which the grooves 22 directly run are formed between the toothed ring 4 and the toothed wheel 12.

In FIG. 1 the toothed wheel 12 occupies the position shown in FIG. 2. The chamber 24 shown at the top is at maximum volume and is marked Max.". During a rotary movement of the toothed wheel 12, the centerpoint M, of the toothed wheel 12 moves along a circular path K about the centerpoint M; of the toothed ring 4. This circular path K has a diameter D. When half the circular path K has been travelled, the upper chamber is at minimum volume. This is marked Min. in FIG.

' 3. FIG. 4 shows the toothed wheel in any given rotary These two arcs are spaced relatively to each other in dependence upon the extent of the circular movement of the toothed wheel 12.

As used herein, an imaginary straight line which extends through points M1 and M2 will be referred to as the line of eccentricity. In operation the line of eccentricity rotates about point M2 at the orbiting speed of toothed wheel 12.

Points M, and M represent the geometric axes of the wheel 12 and the ring 4, respectively, and jointly define a rotating line of eccentricity on opposite sides of which the chambers 24 are expanding or contracting depending on the direction of rotation of the wheel 12.

The valve openings 23 are of triangular form. They extend radially on both sides of the arc T They are constituted by grooves 22 which extend radially and terminate at the middle of the base of each tooth of the wheel 12. They increase in depth towards the circumference of the toothed wheel.

The valve openings 17 and 20 are located alternately along the arc T Each valve opening extends on both sides of this arc. Each valve opening runs mainly from the circumference of the arc towards a path through which a point of the valve opening 23 moves during the circular and rotary movements. The valve openings 17 and 20 thus form a star pattern having a number of points corresponding to the number of teeth of the ring 4 The valve openings 17 and 21 are of the following form: the outer long side a when a chamber having maximum volume is formed (FIG. 2) runs close to the circumference of the wheel 12, but lies completely within the contour of the toothed wheel. One of the short sides b runs close to the valve opening 23 which is here seen in its neutral position. The other short side c is determined in that it runs close to the opposite side I of the valve opening 22 when the toothed wheel has further rotated to an extent equal to half the pitch of the teeth, i.e., when 180 of the circular path K has been travelled. The inner long side d can be moved as far as possible in the radial and inward directions; here, however, it should be ensured that so great a distance is maintained between the long sides d of adjacent valve openings 17 and 21 that these openings do not communicate with each other in the neutral position of the other valve opening 23.

The valve opening 23 is formed only by that part of a groove 22 that is hatched in FIG. 2, since the inner V of this groove is ineffective as regards the functioning of the valve. The radial component R of the valve 23 is roughly equal to the diameter D of the circular path K. In the case of the valve openings 17 and 21 too, the radial component R is approximately equal to the diameter D of the circular path K. When a valve opening 17 and a valve opening 23 cooperate, this results in a registering over the radial width R Furthermore, the two radial components R and R are so selected that the sum of those portions of the radial components that overshootduring registering, that is to say (R R (R R is likewise approximately equal to the diameter D of the circular path K. In other words, the radial width Rb is approximately equal to distance between said radial component and said eccentric distance. In. each case this leads to the valve openings registering over the entire radial width R For the purpose of the following consideration of the motional cycle it will be assumed that the machine is operating as a motor, i.e., that pressurized fluid is supplied through the valve openings 17 and low pressure fluid is discharged through the valve openings 21. Also, the five displacement chambers 24 are marked 24a 24e in the clockwise direction. Then, in the position illustrated in FIG. 2, pressurized fluid is passed into the chamber 24e and low-pressure fluid is discharged from the chamber 24b. The chambers 24a, 24c and 24d are neither connected to the supply side nor to the delivery side. The chamber 24a is at its maximum volume. Chambers 240 and 24d are interconnected through the groove 22. These pressure conditions lead to the toothed wheel rotating in the clockwise direction S. At the same time the centerpoint M moves in the counterclockwise direction along the circular path .K. After brief rotation, the, chamber 24a is connected to the valve opening 21. It is able to reduce its size to the minimum volume (FIG. 3). In this position, the chambers 24b and 24c are connected to the high-pressure side and the chambers 24d and 24e to the low-pressure side. Chamber 24a is cutoff from the supply and discharge sides. The width of the grooves 22 at the circumference of the toothed wheel is such that although the connexion between the chambers 24c and 24d, illustrated in FIG. 2, can be achieved, the points P however, provide a safe seal 24a in the position seen in FIG. 3. FIG. 4 illustrates a position intermediate those of FIGS. 2 and 3 and in which the chamber 24d is connected to the high-pressure side and the chambers 24e and 24a to the low-pressure side, whereas chambers 24b and 24e are not connected-to the supply and discharge sides, but are connected to each other through the valve opening 23.

Similar conditions ated as a pump.

The shape and size of the valve openings can vary from those illustrated to provide the same function as that described. For example, instead of the triangular valve openings 23, a radially extending rectangle can be used. It is also possible to reduce the radial component of the valve openings in one of the sets if this is taken into account by means of a correspondingly great radial component of the valve openings of the other set.

prevail when the machine is oper- We claim:

1. A fluid pressure motor or pump comprising a casing, an internally toothed ring member having an axis, a cooperating externally toothed wheel member having an axis and having fewer teeth than said ring member, said star gear being disposed with its axis being spaced an eccentric distance from said axis of said ring member, said axis of said ring member and said axis of said wheel member jointly defining a line of eccentricity,

said wheel member having rotational movement about its own axis and orbital movement relative to the axis of said ring member with the teeth of said members intermeshing in sealing engagement to form expanding chambers on one side of said line of eccentricity and contracting chambers on the other side of said line during relative movement between said members, said casing forming wall means adjacent said member, two sets of recessed inlet and outlet ports defined in said wall means, fluid inlet and outlet passages in said casing extending to said recessed ports, a set of recessed distributor ports defined in said wheel member, said distributor ports being sequentially registerable with said inlet and outlet ports to alternately receive fluid from said inletports and exhausting fluid to said outlet ports, at least one of said sets of inlet and outlet ports has a radial component at least equal to twice said eccentric distance.

2. A motor or pump according to claim 1 wherein one of said inlet and outlet ports has a radial width equal to the difference between said radial component and said radial component eccentric distance.

3. A'motor or pump according toclaim 1 wherein said distributor ports extend mainly in a radial direction and each distributor port has a radial component at least equal to twice said eccentric distance.

4. A motor or pump according to claim 1 wherein said distributor ports are triangularly shaped.

5. A motor or pump according to claim 1 wherein said recessed distributor ports are between the teeth of said wheel member, said distributor ports having circumferentially extending widths on the periphery of said wheel member sufficient so that one of said distributor ports connects adjacent ones of said chambers when said adjacent chambers are symmetrically disposed relative to said one of said distributor ports. 

1. A fluid pressure motor or pump comprising a casing, an internally toothed ring member having an axis, a cooperating externally toothed wheel member having an axis and having fewer teeth than said ring member, said star gear being disposed with its axis being spaced an eccentric distance from said axis of said ring member, said axis of said ring member and said axis of said wheel member jointly defining a line of eccentricity, said wheel member having rotational movement about its own axis and orbital movement relative to the axis of said ring member with the teeth of said members intermeshing in sealing engagement to form expanding chambers on one side of said line of eccentricity and contracting chambers on the other side of said line during relative movement between said members, said casing forming wall means adjacent said member, two sets of recessed inlet and outlet ports defined in said wall means, fluid inlet and outlet passages in said casing extending to said recessed ports, a set of recessed distributor ports defined in said wheel member, said distributor ports being sequentially registerable with said inlet and outlet ports to alternately receive fluid from said inlet ports and exhausting fluid to said outlet ports, at least one of said sets of inlet and outlet ports has a radial component at least equal to twice said eccentric distance.
 2. A motor or pump according to claim 1 wherein one of said inlet and outlet ports has a radial width equal to the difference between said radial component and said radial component eccentric distance.
 3. A motor or pump according to claim 1 wherein said distributor ports extend mainly in a radial direction and each distributor port has a radial component at least equal to twice said eccentric distance.
 4. A motor or pump according to claim 1 wherein said distributor ports are triangularly shaped.
 5. A motor or pump according to claim 1 wherein said recessed distributor ports are between the teeth of said wheel member, said distributor ports having circumferentially extending widths on the periphery of said wheel member sufficient so that one of said distributor ports connects adjacent ones of said chambers when said adjacent chambers are symmetrically disposed relative to said one of said distributor ports. 